Good for him. He was always a nice young man and carrier himself well. Shame it did not work out for him on the field. Hopefully, he has a satisfying career as a coach.What I found in Illi's website
Sitkowski served as a student assistant in 2023
so your guess of volunteer is probably right when he was a student assistant ( working for free , maybe just tuition being covered part of job) and as a grad assistant ( this year) getting paid and taking a graduate course
>Artur Sitkowski - Graduate Assistant Coach, Offense - Staff Directory - University of Illinois Athletics<
https://fightingillini.com/staff-directory/artur-sitkowski/2028